This program is aimed at studying the mechanism of DNA synthesis of two multienzyme complexes. One complex requires for activity a double stranded DNA template, ATP, Mg ions and four deoxynucleoside triphosphates. This complex is inhibited by actinomycin, ara CTP and nalidixic acid but is resistant to rifamycin. The other multienzyme complex requires circular single stranded DNA, Mg ions, the four ribonucleoside triphosphates and the four deoxyribonucleoside triphosphates for activity. This complex is inhibited by actinomycin, araCTP, and rifamycin. We are trying to determine the nature of the proteins present in these complexes and their role in the overall synthesis of DNA. We are also trying to determine the mechanism of inhibition of selected antitumor agents and antibiotics like araCTP, dauonomycin and nalidixic acid.